It has been customary in the electronic article surveillance (EAS) industry to apply to articles to be monitored disposable adhesive EAS tags or labels functioning as article monitoring devices. At article checkout stations in retail stores, a checkout clerk passes the article over deactivation apparatus which deactivates the monitoring device.
Known deactivation apparatus includes coil structure energizable to generate a magnetic field of magnitude sufficient to render the monitoring device inactive, i.e., no longer responsive to incident energy to itself provide output alarm or to transmit an alarm condition to an alarm unit external to the tag.
One commercial deactivator of the assignee hereof employs one coil disposed horizontally within a housing and tagged articles are moved across the horizontal top surface of the housing such that the tag is disposed generally coplanarly with the coil.
In the normal course of events, the checkout operator deactivates the tag at the checkout station and the customer exits the store with the tagged article.
It is customary in EAS installations to provide a so-called "store exit station" to insure that tagged articles are not removed from a premise in non-deactivated state. Should an article with a tag not deactivated enter the store exit station, an alarm condition is called for.
At times, the deactivation of the checked out article tag is not effective. This results in embarrassment at the store exit station and the possible loss of future shopping in the store by the customer. To avert this situation, the prior art has looked to a "double check station" adjacent the checkout station and remote from the store exit station. The double check station interrogates the article tag, following intended deactivation thereof, and alerts the checkout clerk if indeed the article tag has indeed not been deactivated.
The double check station, while effective in avoiding embarrassment, the operator simply repeating the deactivation cycle and the double check, is manifestly inefficient in requiring additional equipment and space consumption at the checkout station.
The prior art also teaches the use of a single system both to sense the presence of a tag at a deactivation station, to call then for deactivation and then to repeat tag detection, such as is disclosed in U.S. Pat. Nos. 3,938,044 and 4,881,061. However, to the extent that the same detection sensitivity applies to the tag presence sensing and the repeat tag detection, where the tag, following deactivation efforts, is more distal from the detecting antenna, errors can arise, particularly with respect to partially deactivated tags.